The present invention relates to a surface acoustic wave resonator and, more particularly, to an assembly of a surface acoustic wave resonator having arrays of electrodes and reflectors made of piezoelectric material provided on a base plate made of non-piezoelectric material.
Conventionally, there have been proposed various types of surface acoustic wave resonators, and one example is shown in FIG. 1. As illustrated in FIG. 1 in a perspective view, a conventional surface acoustic wave resonator includes a base plate 13, interleaved electrodes 11 disposed on base plate 13 for the excitation and for receiving the surface acoustic wave, and a pair of reflection strip arrays 12a and 12b also disposed on the base plate 13 enclosing the interleaved electrodes 11 for reflecting the excited surface acoustic wave. In the conventional surface acoustic wave resonator, the base plate is generally made of a single-crystal piezoelectric material such as LiNbO.sub.3 or quartz. In the case where the base plate is made of LiNbO.sub.3, there has been a disadvantage that the resonance frequency is not stable with respect to temperature change. A base plate made of quartz provides a stable resonance frequency with respect to temperature change. However, for propagating the surface acoustic wave having a predetermined frequency, it is necessary to select an appropriate quartz which has a particular crystal structure from the view point of crystal face and crystallographic axis.
In general, the material which constitutes the base plate is piezoelectric material and, for the purpose of obtaining a resonator having a high quality, it is necessary to select a base plate having a high quality.